Augmenting Li-ion batteries to the Leaf for higher capacity

Is there a forum or a facebook page that discusses the possibility of augmenting the leaf battery with a parallel battery pack (about 700 Li-ion 18650s 14 Wh cells)?

I hope to increase my Leaf capacity to 34 kWh. 24 kWh is just not enough where there is no L3.

Thanks

Good luck.
Please let us know of your progress.

Also please be VERY careful.

Interleaf said:

Is there a forum or a facebook page that discusses the possibility of augmenting the leaf battery with a parallel battery pack (about 700 Li-ion 18650s 14 Wh cells)?

I hope to increase my Leaf capacity to 34 kWh. 24 kWh is just not enough where there is no L3.

Click to expand...

I suspect it is only a matter of time before somebody does this. It shouldn't be much different than the mods people do to the Toyota Prius and other hybrids to give them plug-in ability. The main issue would be charging the extra battery pack, and of course the extra weight.

adric22 said:

I suspect it is only a matter of time before somebody does this. It shouldn't be much different than the mods people do to the Toyota Prius and other hybrids to give them plug-in ability. The main issue would be charging the extra battery pack, and of course the extra weight.

Click to expand...

The main issue would be hacking Nissan's firmware.

Presumably the added batteries would be voltage matched to the existing battery?
So it would just appear as having larger capacity to the firmware?

Would the new cells have a similar cell voltage as the ones in the leaf? And if they
are slightly off, can you mix them?

evnow said:

The main issue would be hacking Nissan's firmware.

Click to expand...

There would be no need, just like the firmware on the Prius does not require hacking most of the time. In the case of the Leaf it would be even easier. Granted, the Leaf may not be aware of the extra range. It may start off in the morning saying 100 miles, even though in theory you should have more than that. But I would imagine the mileage estimate would simply drop more slowly than usual as it watches the voltage sag in the battery pack.

The main challenges would be similar to those in the Prius. Where to mount the pack? Will the suspension need to be upgraded? How will the new cells be balanced and maintained? Will they be charged from the main leaf charger, or need to be charged separately?

evnow said:

The main issue would be hacking Nissan's firmware.

Click to expand...

That's exactly what I suspected. The firmware will probably fault in multiple places. It may even report the hack via carwings or via memory to the dealer, and invalidate the warranty.

If one finds the two leads out of the onboard battery pack, and parallels that (i.e. no charging or balancing of the extra pack via the onboard charger) do you think the firmware is programmed to detect a mismatch in capacity and initiate a fault?

Interleaf said:

If one finds the two leads out of the onboard battery pack, and parallels that (i.e. no charging or balancing of the extra pack via the onboard charger) do you think the firmware is programmed to detect a mismatch in capacity and initiate a fault?

Click to expand...

I have upgraded several Prius's, so I'm quite familiar with this. What you are concerned about is that the battery ECU will be reporting a certain amount of amperage coming out and the main inverter/controller will be detecting something different. The Prius will tolerate a certain amount of difference, probably to account for other equipment such as the air conditioner which also drains power. Some kits, such as the Enginer kit, will connect to the outside terminals of the battery but are limited to a certain number of amps so as to not upset the Prius computers. However, other kits will connect on the inside of the battery pack, thereby pumping power in behind the current sensor so the car has no idea that amperage is coming from anywhere other than the battery pack itself.

Weight, volume & charging should not be issues.

10 kWh / 14 = 714 -- 18650 cells. Assuming Leaf battery = 370 volts, then that would be 8P100S or 800 cells for a total capacity of 11 kWh.

Weight = 800 X.050 x 110% = 44 kg (including associated packaging & connections). That is about half the weight of an average male passenger.

Volume = 800 x 18^2 x 65 x 80% (triangular packing) x 110% (packaging) = 14 litres or 8 in x 8 in x 14 in. Easily fits in the trunk, or even under the hood, when required. The extra pack will only be required when the driver anticipates a long drive. It can be removed.

Charging - will be via a separate BMS to allow for parallel charging with the Leaf. A 220v 3.3 kW charger will fill it up in 3.5 hours. This can be done while the pack is in the trunk (fire hazard?)

Cost = 800 * $2 = $1,600 not including the charger & cabling.

18650 cells are state of the art in both weight and volume density. Cheap cells may not give you 3000 cycles, but costing about $2 each in volume, they are replacable. Besides the extra pack will probably cycle only 1/4 as many as the onboard battery.

I have no hope at all that it would be possible to use the onboard charger and balancing system. But then using a separate charger and BMS means I get faster charging.

adric22 said:

I have upgraded several Prius's, so I'm quite familiar with this. What you are concerned about is that the battery ECU will be reporting a certain amount of amperage coming out and the main inverter/controller will be detecting something different. The Prius will tolerate a certain amount of difference, probably to account for other equipment such as the air conditioner which also drains power. Some kits, such as the Enginer kit, will connect to the outside terminals of the battery but are limited to a certain number of amps so as to not upset the Prius computers. However, other kits will connect on the inside of the battery pack, thereby pumping power in behind the current sensor so the car has no idea that amperage is coming from anywhere other than the battery pack itself.

Click to expand...

Interesting adric22 -- If the extra pack is connected to a point past the ECU (i.e. at the inverter), then the Leaf would think it is on a downhill roll, as it is using less power, but going further than usual.

If it is connected before the ECU, the Leaf might wonder why the voltage does not drop as quickly as it should, given the current drain?

Interleaf said:

Weight, volume & charging should not be issues.

10 kWh / 14 = 714 -- 18650 cells. Assuming Leaf battery = 370 volts, then that would be 8P100S or 800 cells for a total capacity of 11 kWh.

Weight = 800 X.050 x 110% = 44 kg (including associated packaging & connections). That is about half the weight of an average male passenger.

Volume = 800 x 18^2 x 65 x 80% (triangular packing) x 110% (packaging) = 14 litres or 8 in x 8 in x 14 in. Easily fits in the trunk, or even under the hood, when required. The extra pack will only be required when the driver anticipates a long drive. It can be removed.

Charging - will be via a separate BMS to allow for parallel charging with the Leaf. A 220v 3.3 kW charger will fill it up in 3.5 hours. This can be done while the pack is in the trunk (fire hazard?)

Cost = 800 * $2 = $1,600 not including the charger & cabling.

18650 cells are state of the art in both weight and volume density. Cheap cells may not give you 3000 cycles, but costing about $2 each in volume, they are replacable. Besides the extra pack will probably cycle only 1/4 as many as the onboard battery.

I have no hope at all that it would be possible to use the onboard charger and balancing system. But then using a separate charger and BMS means I get faster charging.

Click to expand...

It's fun to crunch theoretical numbers on paper but actually building a safe, reliable and low-weight traction pack as you described is not that simple. Your figures for weight are grossly off and you are making quite a few assumptions. To simplify this idea, it would be a significant feat to build a quality 10kw integrated pack addition for a LEAF at even close to an affordable price. What you suggest in a quality, reliable and safe form is not even likely at a cost factor of 10X without mass production.

EVDRIVER said:

It's fun to crunch theoretical numbers on paper but actually building a safe, reliable and low-weight traction pack as you described is not that simple. Your figures for weight are grossly off and you are making quite a few assumptions. To simplify this idea, it would be a significant feat to build a quality 10kw integrated pack addition for a LEAF at even close to an affordable price. What you suggest in a quality, reliable and safe form is not even likely at a cost factor of 10X without mass production.

Click to expand...

"figures for weight are grossly off" -- An 18650 weighs 45 grams to 50 grams. Can you do the calculation for weight and show me where I am wrong?

"reliable" -- remember this is a secondary battery pack. If it occasionaly fails due to a bad cell, it is not the end of the world. One can even easily replace the bad cell in the field.

"saety" --well the 18650 has shown to be quite safe. Tesla is based on it, and you dont hear of laptop fires anymore. A temprature alarm in the case can warn the driver before it turns into a fire torch!

What are the "assumptions" that I am making, except for issues with the Leaf's firmware?

"quality package" -- I think you mistakenly assume that I want to make a commercial product. Not really, this is just one of a kind.

And 18650s indeed do cost $2 each (at 14 Wh). Check Ebay.

klapauzius said:

Presumably the added batteries would be voltage matched to the existing battery?
So it would just appear as having larger capacity to the firmware?

Would the new cells have a similar cell voltage as the ones in the leaf? And if they
are slightly off, can you mix them?

Click to expand...

I don't think it is advisable to connect the two batteries in the 2P100S configuration. Then you depend on matching the chemistries, and defeating a lot of electronics. Much simpler would be the 100S2P configuration, where you can have different number of cells than the Leaf.

So no, you dont need to precisely match the Leaf battery.

The big question is if the firmware is going to belch, and how to get around that while increasing the Leaf's capacity by 50%.

Interleaf said:

EVDRIVER said:

It's fun to crunch theoretical numbers on paper but actually building a safe, reliable and low-weight traction pack as you described is not that simple. Your figures for weight are grossly off and you are making quite a few assumptions. To simplify this idea, it would be a significant feat to build a quality 10kw integrated pack addition for a LEAF at even close to an affordable price. What you suggest in a quality, reliable and safe form is not even likely at a cost factor of 10X without mass production.

Click to expand...

"figures for weight are grossly off" -- An 18650 weighs 45 grams to 50 grams. Can you do the calculation for weight and show me where I am wrong?

"reliable" -- remember this is a secondary battery pack. If it occasionaly fails due to a bad cell, it is not the end of the world. One can even easily replace the bad cell in the field.

"saety" --well the 18650 has shown to be quite safe. Tesla is based on it, and you dont hear of laptop fires anymore. A temprature alarm in the case can warn the driver before it turns into a fire torch!

What are the "assumptions" that I am making, except for issues with the Leaf's firmware?

"quality package" -- I think you mistakenly assume that I want to make a commercial product. Not really, this is just one of a kind.

And 18650s indeed do cost $2 each (at 14 Wh). Check Ebay.

Click to expand...

Have you ever built a traction pack, not a bunch of batteries assembled together on paper off an ebay search? The weight alone is not some cells stuck in a cardboard box or between plumbers tape. There is safe and secure packaging, well built connections, BMS, software, connections to the car, etc, etc. If you think it's that simple and inexpensive then try to build one and get back to us all in six months. Reliable goes much much more than some failing cells. I wish I had a dollar for every traction pack built on paper or conversion spreadsheet that never even came close to the estimated time and cost. Forget a commercial product, just attempt "home built" and working and see how that process progresses based on your "estimates". Everything sounds cheap and easy until you actually do it.

is $2 per cell realistic? If looking for this type off ebay, you pay more like
$10 per cell....and those are 9 wh.

so there is a factor of 10 already in the cost of the battery.

EVDRIVER said:

Have you ever built a traction pack, not a bunch of batteries assembled together on paper off an ebay search? The weight alone is not some cells stuck in a cardboard box or between plumbers tape. There is safe and secure packaging, well built connections, BMS, software, connections to the car, etc, etc. If you think it's that simple and inexpensive then try to build one and get back to us all in six months. Reliable goes much much more than some failing cells. I wish I had a dollar for every traction pack built on paper or conversion spreadsheet that never even came close to the estimated time and cost. Forget a commercial product, just attempt "home built" and working and see how that process progresses based on your "estimates". Everything sounds cheap and easy until you actually do it.

Click to expand...

I hear you, but I fail to see the great challenge. "Safe & secure packeging" Why do you need more than a metal box and some good insulation? Remember, we are on a shoestring.

"Well built connections" - It's called a soldering iron (spot welder to be fancy), some 14 gauge wire, and some cable that can handle 100 amps, and some decent low current connectors, and some terminals that can handle 100 amps.

BMS: just buy some off the shelf units.

software/ connection to the car - yes, I have already acknowledged this as the challenge.

klapauzius said:

is $2 per cell realistic? If looking for this type off ebay, you pay more like
$10 per cell....and those are 9 wh.

so there is a factor of 10 already in the cost of the battery.

Click to expand...

Hmmm.... I fail to find $10 cells on Ebay. The most expensive is $4.00.

14 Wh for $1.70? Here it is:

http://www.ebay.com/itm/10-x-3800mAh-18650-rechargeable-battery-UitraFire-JJ0-/300547142222?pt=US_Batteries&hash=item45fa01724e142" onclick="window.open(this.href);return false;

more here:

http://www.ebay.com/sch/i.html?_nkw=18650" onclick="window.open(this.href);return false;

evnow said:

adric22 said:

I suspect it is only a matter of time before somebody does this. It shouldn't be much different than the mods people do to the Toyota Prius and other hybrids to give them plug-in ability. The main issue would be charging the extra battery pack, and of course the extra weight.

Click to expand...

The main issue would be hacking Nissan's firmware.

Click to expand...

One solution is to not hack the firmware at all. Apparently, you can dump into the battery at 20-30kW with no alarms being triggered.

That solution is actively being worked on now.

Interleaf said:

klapauzius said:

is $2 per cell realistic? If looking for this type off ebay, you pay more like
$10 per cell....and those are 9 wh.

so there is a factor of 10 already in the cost of the battery.

Click to expand...

Hmmm.... I fail to find $10 cells on Ebay. The most expensive is $4.00.

14 Wh for $1.70? Here it is:

http://www.ebay.com/itm/10-x-3800mAh-18650-rechargeable-battery-UitraFire-JJ0-/300547142222?pt=US_Batteries&hash=item45fa01724e142" onclick="window.open(this.href);return false;

more here:

http://www.ebay.com/sch/i.html?_nkw=18650" onclick="window.open(this.href);return false;

Click to expand...

I meant NOT on ebay. Sometimes stuff you buy there has dubious quality,
but I may be wrong... 140 Wh for $17 seems very cheap. Did you try those out?

klapauzius said:

is $2 per cell realistic? If looking for this type off ebay, you pay more like
$10 per cell....and those are 9 wh.

Click to expand...

I was tempted to mention this as well. I have tried long and hard to source 18650 cells for my laptop business where I refurbish them. Unfortunately, by the time I buy 6 to 10 cells (depending on laptop) it more or less equals what I can buy an aftermarket battery pack for with the cells already in there. Unless you are buying them 100,000 at a time, you'll never get a price anywhere near that. I think the last ones I bought were about $7 a piece.

Now, factor in battery balancers. those will probably cost more than the batteries themselves, or at least darned close. 18650 cells are useless without systems in place to protect them from being over or under charged.

Also need to factor in structural components. You need something to hold all of these cells. That is going to add extra weight.

Now when we've mentioned safety... it isn't just the cells that need to be safe. The whole system has to be safe. There have to be fuses and relays and insulators and all kinds of things in place to make sure the lethal and hazardous amount of power in such a pack can never cause a fire or electrocute somebody. But there is even more to it than that.. You need to take the safety of the vehicle into account. What happens when the vehicle is in an accident? Will the add-on pack be safe? Will it come flying forward into the passenger area and kill somebody? Will it explode because a short circuit was created inside due to it being crushed? Also need to have safety mechanisms in place that make sure power is disconnected when the car is shut off. Also need to make sure that the system won't damage the Leaf's existing battery by overcharging parts of it, or maybe even draining parts of it when the car is off for long periods.

I'm not trying to say this can't be done. But it is a huge engineering undertaking to make it work and make it safe. Just ask all of the people who've upgraded their Prius. It is the same concept. I highly suspect you'd be looking at $13,000 or more for a mass-produced kit to give anywhere near 10Kwh of power.